NEW YORK (AP) -- Hundreds of people holding pens aloft in support of free expression rallied in New York City on Saturday to mourn victims of a deadly terror attack targeting a French satirical publication.

The demonstrators braved freezing temperatures in Manhattan's Washington Square Park as a woman danced under a sign that read "Je suis Charlie."

"I am Charlie" has emerged as a rallying cry since two shooters killed 12 people Wednesday at the Paris headquarters of the satirical magazine Charlie Hebdo. Organizers said they were showing solidarity with the French after three days of violence that, all told, left 20 dead, including three gunmen.

Ollivier Souchard, a French-born New York resident who brought his family and friends, explained the fierce support for freedom of expression behind Charlie Hebdo's provocative images.

"What we are afraid of is less freedom for more security, it's muzzling," Souchard said.

Making a fist and tapping it over his heart, he added, "Satirical cartoons are essential to us, they're essential to France. We were raised with great cartoons, but you Americans don't like to hurt people with cartoons- but you should hurt people!"

"Charlie Hebdo would not exist in America," Souchard said.

Souchard said he has been in touch with his friend Philippe Lancon, a Charlie Hebdo columnist who is recovering from surgery after being shot in the face in the attack.

The New York march came after hundreds of thousands rallied hours earlier in French cities from Toulouse in the south to Rennes in the west to honor the victims.

A massive rally is planned for Sunday in Paris, where an additional 2,000 police are being deployed amid heightened security. Leaders of Britain, Germany, NATO and the Arab League are among dozens of world dignitaries expected to attend.